Old Testament you would have a point as the Hebrew people were a political unit, New Testament, not so much since its based around everybody. Animals were not given a set of rules either so I don't really see animal behavior as being particularly relevant. The theory of it being strictly population based is interesting, but I do not see scriptoral evidence to support it as is. I'm not certain about eating certain meats on certain days except some of the old festivals, I have no idea why Catholics do that during lent really. The lifting of the ban on certain meats has a pair of scripture bases about its absolution. I believe the specific reason given was that it was unclean (ie bad for you), but if I recall correctly many of them were given specifically to the Hebrews. As a Celt/Teuton I'm honestly not certain it would have any sway anyway give my people were not the target of the command.